The objective of the proposed research is to use nuclear magnetic resonance spectroscopic techniques to obtain information about the structure and the function of a variety of respiratory proteins, membrane proteins, and protein lipid complexes. Fourier transform NMR spectrometers will be used to study 31P, 2H, and 13C NMR of these systems to answer the following questions: What is the nature of protein lipid interaction in biological membranes? What are the differences, if any, between the structures of proteins in solution, in the crystalline solid state and in membranes? Deuterium and carbon-13 NMR are being used to investigate the dynamics of protein lipid interaction between cytochrome oxidase and a variety of lipids using 2H quadrupole splittings and relaxation times and 31P chemical shielding anisotropies and relaxation times together with C-13 NMR chemical shifts and dipolar splittings. Efforts are being made to investigate protein dynamics in membranes by 2H and 13C labelling, with special emphasis on determining the effect of lipid phase structure on protein dynamics.